A radio frame in a Long Term Evolution (LTE) system comprises frame structures in a Frequency Division Duplex (FDD) mode and in a Time Division Duplex (TDD) mode. As shown in FIG. 1, in the frame structure in the FDD mode, one radio frame of 10 ms is composed of 20 time slots, wherein the length of each time slot is 0.5 ms and the 20 time slots are numbered from 0 to 19; the time slots 2i and 2i+1 compose a subframe i, the length of which is 1 ms. As shown in FIG. 2, in the frame structure in the TDD mode, one radio frame of 10 ms is composed of two half frames, wherein the length of each half frame is 5 ms; one half frame comprises 5 subframes, wherein the length of each subframe is 1 ms; the subframe i is defined as two time slots 2i and 2i+1, wherein the length of each time slot is 0.5 ms. In the above-mentioned two frame structures, for a Normal Cyclic Prefix (Normal CP), one time slot comprises 7 symbols, wherein the length of each symbol is 66.7 us, and a CP length of the first symbol is 5.21 us, and lengths of the rest 6 symbols are 4.69 us; for an Extended Cyclic Prefix (Extended CP), one time slot comprises 6 symbols, wherein the CP lengths of all the symbols are 16.67 us.
A piece of User Equipment (UE) obtains downlink channel quality information according to a downlink pilot frequency (reference signal), and then feeds back the obtained downlink channel quality information to an eNB (base station); the base station determines a code modulation mode of data sent to the UE, a physical resource location and a transmission mode according to the downlink channel quality information fed back by the UE. There are two ways of feeding back the downlink channel quality information by the UE, one is periodic feedback, and the other is non-periodic feedback, wherein the periodic feedback is performing feedback according to a prescribed period, and the non-periodic feedback is that the base station triggers the UE to perform feedback through a downlink signaling.
In the LTE system, the base station triggers the UE to perform non-periodic feedback through 1-bit signaling in a Downlink Control Information (DCI) format 0; furthermore, feedback information is borne through a Physical Uplink Shared Channel (PUSCH), and the DCI information is transmitted through a Physical Downlink Control Channel (PDCCH).
A Long-Term Evolution Advanced (LTE-A) system is an evolution version of LTE Release-8. An advanced international wireless communication system presented by International Telecommunications Union-Radio Communications Sector (ITU-R) requires backward compatibility. Requirement for backward compatibility between the LTE-Advanced and the LTE Release-8 means that the UE of the LTE Release-8 can operate in an LTE-Advanced network; and the UE of the LTE-Advanced can operate in an LTE Release-8 network. In addition, the LTE-Advanced should be able to operate in configurations of frequency spectrum with different sizes, comprising configuration of frequency spectrum which is wider than that of the LTE Release-8 (e.g., the configuration of wider frequency spectrum being continuous frequency spectrum resource of 100 MHz), so as to achieve higher performance and target peak rate. In view of the compatibility with the LTE Release-8, for bandwidth which is more than 20 MHz, a way of carrier aggregation is adopted, that is, two or more than two component carriers (CC) are aggregated to support downlink transmission bandwidth which is more than 20 MHz. In the LTE-A system, it is supported that a Downlink Component Carrier (DL CC) sends scheduling information (DCI Format) of other DL CC, and a Carrier Indicator (CI) signaling is introduced in a DCI Format domain for identifying the scheduled DL CC or Uplink Component Carrier (UL CC).
The inventor finds that when multiple component carries are aggregated, meaning of a non-periodic trigger signaling is not defined in relevant technologies, that is, it is not indicated in the non-periodic trigger signaling that the downlink channel quality information of which component carrier is to be triggered non-periodically, as a result, the UE is unable to determine which downlink component carrier is to be fed back according to the non-periodic trigger signaling, and further the base station is unable to ensure the performance of downlink data transmission. Aiming at the problem, no effective solution has been presented.